This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | -1 |
| 1 | 9 |
| 2 | 161 |
| 3 | 1665 |
| 4 | 14849 |
| 5 | 124929 |
| 6 | 1024001 |
| 7 | 8290305 |
| 8 | 66715649 |
| 9 | 535298049 |
| 10 | 4288675841 |
| 11 | 34334572545 |
| 12 | 274777243649 |
| 13 | 2198620602369 |
| 14 | 17590575431681 |
| 15 | 140731045904385 |
| 16 | 1125874137038849 |
| 17 | 9007096175525889 |
| 18 | 72057181721067521 |
| 19 | 576459103035981825 |
| 20 | 4611679421357621249 |
| 21 | 36893461759140036609 |